openssl/crypto/bn/bn_blind.c

299 lines
7.6 KiB
C

/*
* Copyright 1998-2023 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <openssl/opensslconf.h>
#include "internal/cryptlib.h"
#include "bn_local.h"
#define BN_BLINDING_COUNTER 32
BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
{
BN_BLINDING *ret = NULL;
bn_check_top(mod);
if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
return NULL;
}
ret->lock = CRYPTO_THREAD_lock_new();
if (ret->lock == NULL) {
BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
OPENSSL_free(ret);
return NULL;
}
BN_BLINDING_set_current_thread(ret);
if (A != NULL) {
if ((ret->A = BN_dup(A)) == NULL)
goto err;
}
if (Ai != NULL) {
if ((ret->Ai = BN_dup(Ai)) == NULL)
goto err;
}
/* save a copy of mod in the BN_BLINDING structure */
if ((ret->mod = BN_dup(mod)) == NULL)
goto err;
if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
BN_set_flags(ret->mod, BN_FLG_CONSTTIME);
/*
* Set the counter to the special value -1 to indicate that this is
* never-used fresh blinding that does not need updating before first
* use.
*/
ret->counter = -1;
return ret;
err:
BN_BLINDING_free(ret);
return NULL;
}
void BN_BLINDING_free(BN_BLINDING *r)
{
if (r == NULL)
return;
BN_free(r->A);
BN_free(r->Ai);
BN_free(r->e);
BN_free(r->mod);
CRYPTO_THREAD_lock_free(r->lock);
OPENSSL_free(r);
}
int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
{
int ret = 0;
if ((b->A == NULL) || (b->Ai == NULL)) {
BNerr(BN_F_BN_BLINDING_UPDATE, BN_R_NOT_INITIALIZED);
goto err;
}
if (b->counter == -1)
b->counter = 0;
if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
!(b->flags & BN_BLINDING_NO_RECREATE)) {
/* re-create blinding parameters */
if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
goto err;
} else if (!(b->flags & BN_BLINDING_NO_UPDATE)) {
if (b->m_ctx != NULL) {
if (!bn_mul_mont_fixed_top(b->Ai, b->Ai, b->Ai, b->m_ctx, ctx)
|| !bn_mul_mont_fixed_top(b->A, b->A, b->A, b->m_ctx, ctx))
goto err;
} else {
if (!BN_mod_mul(b->Ai, b->Ai, b->Ai, b->mod, ctx)
|| !BN_mod_mul(b->A, b->A, b->A, b->mod, ctx))
goto err;
}
}
ret = 1;
err:
if (b->counter == BN_BLINDING_COUNTER)
b->counter = 0;
return ret;
}
int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
{
return BN_BLINDING_convert_ex(n, NULL, b, ctx);
}
int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
{
int ret = 1;
bn_check_top(n);
if ((b->A == NULL) || (b->Ai == NULL)) {
BNerr(BN_F_BN_BLINDING_CONVERT_EX, BN_R_NOT_INITIALIZED);
return 0;
}
if (b->counter == -1)
/* Fresh blinding, doesn't need updating. */
b->counter = 0;
else if (!BN_BLINDING_update(b, ctx))
return 0;
if (r != NULL && (BN_copy(r, b->Ai) == NULL))
return 0;
if (b->m_ctx != NULL)
ret = BN_mod_mul_montgomery(n, n, b->A, b->m_ctx, ctx);
else
ret = BN_mod_mul(n, n, b->A, b->mod, ctx);
return ret;
}
int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
{
return BN_BLINDING_invert_ex(n, NULL, b, ctx);
}
int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b,
BN_CTX *ctx)
{
int ret;
bn_check_top(n);
if (r == NULL && (r = b->Ai) == NULL) {
BNerr(BN_F_BN_BLINDING_INVERT_EX, BN_R_NOT_INITIALIZED);
return 0;
}
if (b->m_ctx != NULL) {
/* ensure that BN_mod_mul_montgomery takes pre-defined path */
if (n->dmax >= r->top) {
size_t i, rtop = r->top, ntop = n->top;
BN_ULONG mask;
for (i = 0; i < rtop; i++) {
mask = (BN_ULONG)0 - ((i - ntop) >> (8 * sizeof(i) - 1));
n->d[i] &= mask;
}
mask = (BN_ULONG)0 - ((rtop - ntop) >> (8 * sizeof(ntop) - 1));
/* always true, if (rtop >= ntop) n->top = r->top; */
n->top = (int)(rtop & ~mask) | (ntop & mask);
n->flags |= (BN_FLG_FIXED_TOP & ~mask);
}
ret = BN_mod_mul_montgomery(n, n, r, b->m_ctx, ctx);
} else {
ret = BN_mod_mul(n, n, r, b->mod, ctx);
}
bn_check_top(n);
return ret;
}
int BN_BLINDING_is_current_thread(BN_BLINDING *b)
{
return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
}
void BN_BLINDING_set_current_thread(BN_BLINDING *b)
{
b->tid = CRYPTO_THREAD_get_current_id();
}
int BN_BLINDING_lock(BN_BLINDING *b)
{
return CRYPTO_THREAD_write_lock(b->lock);
}
int BN_BLINDING_unlock(BN_BLINDING *b)
{
return CRYPTO_THREAD_unlock(b->lock);
}
unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
{
return b->flags;
}
void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
{
b->flags = flags;
}
BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
int (*bn_mod_exp) (BIGNUM *r,
const BIGNUM *a,
const BIGNUM *p,
const BIGNUM *m,
BN_CTX *ctx,
BN_MONT_CTX *m_ctx),
BN_MONT_CTX *m_ctx)
{
int retry_counter = 32;
BN_BLINDING *ret = NULL;
if (b == NULL)
ret = BN_BLINDING_new(NULL, NULL, m);
else
ret = b;
if (ret == NULL)
goto err;
if (ret->A == NULL && (ret->A = BN_new()) == NULL)
goto err;
if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
goto err;
if (e != NULL) {
BN_free(ret->e);
ret->e = BN_dup(e);
}
if (ret->e == NULL)
goto err;
if (bn_mod_exp != NULL)
ret->bn_mod_exp = bn_mod_exp;
if (m_ctx != NULL)
ret->m_ctx = m_ctx;
do {
int rv;
if (!BN_priv_rand_range(ret->A, ret->mod))
goto err;
if (int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv))
break;
/*
* this should almost never happen for good RSA keys
*/
if (!rv)
goto err;
if (retry_counter-- == 0) {
BNerr(BN_F_BN_BLINDING_CREATE_PARAM, BN_R_TOO_MANY_ITERATIONS);
goto err;
}
} while (1);
if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL) {
if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
goto err;
} else {
if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
goto err;
}
if (ret->m_ctx != NULL) {
if (!bn_to_mont_fixed_top(ret->Ai, ret->Ai, ret->m_ctx, ctx)
|| !bn_to_mont_fixed_top(ret->A, ret->A, ret->m_ctx, ctx))
goto err;
}
return ret;
err:
if (b == NULL) {
BN_BLINDING_free(ret);
ret = NULL;
}
return ret;
}